This invention relates to systems and methods for processing and collecting blood, blood constituents, or other suspensions of cellular material.
Today people routinely separate whole blood, usually by centrifugation, into its various therapeutic components, such as red blood cells, platelets, and plasma.
Conventional blood processing methods use durable centrifuge equipment in association with single use, sterile processing systems, typically made of plastic. The operator loads the disposable systems upon the centrifuge before processing and removes them afterwards.
Conventional blood centrifuges are of a size that does not permit easy transport between collection sites. Furthermore, loading and unloading operations can sometimes be time consuming and tedious.
In addition, a need exists for further improved systems and methods for collecting blood components in a way that lends itself to use in high volume, on line blood collection environments, where higher yields of critically needed cellular blood components, like plasma, red blood cells, and platelets, can be realized in reasonable short processing times.
The operational and performance demands upon such fluid processing systems become more complex and sophisticated, even as the demand for smaller and more portable systems intensifies. The need therefore exists for automated blood processing controllers that can gather and generate more detailed information and control signals to aid the operator in maximizing processing and separation efficiencies.
The invention provides systems and methods for processing blood and blood constituents that lend themselves to portable, flexible processing platforms equipped with straightforward and accurate control functions.
More particularly, the invention provides red blood cell sensing systems and methods that rely upon straightforward measurement geometries. The systems and methods make possible accurate red blood sensing without use of special optical cuvettes, mirrors, or focusing lenses. The systems and methods also make possible the use of standard transparent plastic tubing, without reliance upon special optical cuvettes.
According to one aspect of the invention, the systems and methods comprise an incident light source, an optical sensor, and a blood collection tube. The systems and methods hold the blood collection tube a predetermined radial distance from the incident light source where a linear relationship exists between sensed reflected light measured by the optical sensor and red blood cell hematocrit in a range of at least 10 to 90.
In one embodiment, the light source has a wavelength of about 805 nm, and the predetermined radial distance is about 7.5 mm from the light source.
According to another aspect of the invention, the systems and methods are used in association with a device for separating whole blood into red blood cells and plasma. In this arrangement, the systems and methods include a sensing assembly outside the device, which includes an incident light source and an optical sensor to sense red blood cells. A fluid circuit coupled to the device includes a component collection tube for conveying a flow of plasma or red blood cells from the device. The systems and methods include a fixture that is movable into releasable engagement with the sensing assembly. The fixture includes a holder to hold the component collection tube a predetermined radial distance from the incident light source where a linear relationship exists between sensed reflected light measured by the optical sensor and red blood cell hematocrit in a range of at least 10 to 90.
In one embodiment, the fluid circuit includes a whole blood inlet tube for conveying a flow of whole blood into the device. In this embodiment, the holder also holds the whole blood inlet tube, so that the fixture serves to gather and hold the whole blood inlet tube and the component collection tube in a bundle.
In one embodiment, the component collection tube comprises transparent flexible tubing that interfaces directly with the sensing assembly and is free of an optical cuvette. The collection tube can covey red blood cells or plasma from the separation device.
Other features and advantages of the inventions are set forth in the following specification and attached drawings.